Anti-DDoS enhancements: Log to net log, UMA stats, improved policy.

net/base/backoff_entry.h

 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef NET_BASE_BACKOFF_ITEM_H_
 #define NET_BASE_BACKOFF_ITEM_H_
 #pragma once
 
 #include "base/threading/non_thread_safe.h"
 #include "base/time.h"
@@ skipping 51 matching lines @@
 
   // Causes this object reject requests until the specified absolute time.
   // This can be used to e.g. implement support for a Retry-After header.
   void SetCustomReleaseTime(const base::TimeTicks& release_time);
 
   // Returns true if this object has no significant state (i.e. you could
   // just as well start with a fresh BackoffEntry object), and hasn't
   // had for Policy::entry_lifetime_ms_.
   bool CanDiscard() const;
 
+  // Resets this entry to a fresh (as if just constructed) state.
+  void Reset();
+
+  // Returns the failure count for this entry.
+  int failure_count() const;

[wtc, 2011/05/25 23:12:06]

Nit: define this getter inline?

[Jói, 2011/05/26 14:53:42]

Done.

+
  protected:
   // Equivalent to TimeTicks::Now(), virtual so unit tests can override.
-  // TODO(joi): Switch to constructor-time dependency injection?
-  virtual base::TimeTicks GetTimeNow() const;
+  virtual base::TimeTicks ImplGetTimeNow() const;

[wtc, 2011/05/25 23:12:06]

Nit: we usually put "Impl" at the end, so "GetTimeNowImpl"?

[Jói, 2011/05/26 14:53:42]

I've been using Impl at the front for methods intended for unit tests to
override. Will leave as-is in this change, but if you think it's best, I can go
through (these files and several others) and rename these methods so that Impl
is at the end.

 
  private:
   // Calculates when requests should again be allowed through.
   base::TimeTicks CalculateReleaseTime() const;
 
   // Timestamp calculated by the exponential back-off algorithm at which we are
   // allowed to start sending requests again.
   base::TimeTicks exponential_backoff_release_time_;
 
   // Counts request errors; reset on success.
   int failure_count_;
 
   const Policy* const policy_;
 
   DISALLOW_COPY_AND_ASSIGN(BackoffEntry);
 };
 
 }  // namespace net
 
 #endif  // NET_BASE_BACKOFF_ITEM_H_